1. Field of the Invention
The present invention relates to an apparatus that uses a high-frequency acceleration type ion beam having an energy spread that is accelerated using a high-frequency accelerator such as a linear accelerator or a synchrotron for an energy analysis.
2. Description of the Related Art
The high-frequency acceleration type acceleration of ions using a high-frequency electric field is used in a high-energy ion implanter that is used for introducing impurities to a silicon wafer, a heavy-ion cancer treatment apparatus that is used for causing cancer cells to disappear in a pinpoint manner, and the like. Different from an ion beam accelerated by a constant voltage, an ion beam (a group of ions) accelerated by a high-frequency electric field has a spread of energy (energy spread) of some degree.
For example, in a high-energy ion implanter that is one of a conventional ion acceleration and transportation apparatus, a simple energy analysis system that is configured by one analysis electromagnet and one energy defining slit are installed to the downstream side of a linear accelerator (high-frequency linear accelerator), a center portion of a beam having an energy spread is cut out, the energy is arranged to be uniform to some degree, and the ion beam is configured to be driven into a silicon wafer.
While the beam accelerated by the high-frequency linear accelerator has an energy spread (energy distribution) of a maximum of several % with respect to the set beam energy due to the oscillation of synchrotron, it is required to adjust the accelerated beam to a smaller energy spread in accordance with a request for high energy precision. In addition, since there are cases where the acceleration phase and the traveling time of ions slightly change depending on the type of the ions and the adjustment state of the high-frequency linear accelerator, there is a possibility that the central value (beam energy) of the energy spread (energy distribution) deviates in the range of several % that is the same degree of the energy spread. Thus, in the case where there is such a slight center energy deviation, the characteristics may get out of order depending on a semiconductor device.